1. Field of the Invention
The present invention relates to a method for producing a liquid-crystalline polyester powder.
2. Description of the Related Art
A liquid-crystalline polyester is preferably used as an injection molding material for the production of a molded article having a thin-wall portion and a molded article having a complicated shape since it is excellent in melt fluidity and also has high heat resistance and mechanical strength. Also, it has recently been studied to use, as a press molding material for the production of a comparatively large-sized molded article, a liquid-crystalline polyester powder in the form of fine particles (see, for example, JP-A-2008-75063)
The liquid-crystalline polyester powder is obtained by obtaining a liquid-crystalline polyester through melt polycondensation, solidifying and then crushing the liquid-crystalline polyester. However, there is a problem that, when a flow initiation temperature of the liquid-crystalline polyester is too high, although high heat resistance and mechanical strength are achieved, it is difficult to crush into fine particles. In order to solve such a problem, for example, JP-A-2003-268121 discloses that a liquid-crystalline polyester powder in the form of fine particles having an average particle diameter of 0.5 to 50 μm is obtained by crushing a liquid-crystalline polyester having a low flow initiation temperature of 200 to 270° C., and also discloses that heat resistance and mechanical strength are enhanced by raising the flow initiation temperature as a heat treatment after crushing.